The cost of telecommunication network operators includes two parts: the capital expenditure (CAPEX: Capital Expenditure) such as network devices, computers, and instruments; and daily operating expenditure (OPEX: Operating Expenditure). At present, the OPEX becomes an important part concerned by operators. For a mobile operator, the cost of the electricity energy consumption accounts for a huge part in the OPEX. Most electricity energy is consumed by the power amplifier of transmit signals. In a LTE (long term evolution) system, the downstream reference signals are necessary for downstream data receiving. Even though there is no data to be sent, the base station needs to regularly transmit downstream reference signals. The factors affecting the transmit power of downstream reference signals are the number of downstream reference signals and the power spectrum density (PSD) of downstream reference signals.